The company, which has a restaurant at the MarketFair mall on Route 1 in West Windsor, said it was working with federal investigators and had changed its payment processing to manual input at all restaurants.

“This ensures our guests can still use their credit and debit cards safely in our restaurants as our investigation continues,” the company said in a statement on its website.

The chain has also established a website where customers can find updates on the security breach: pfchangs.com/security.

P.F. Chang’s advised customers to check their bank and credit card statements carefully to catch any instances of fraud.

“Because we are still in the preliminary stages of our investigation, we encourage our guests to be vigilant about checking,” the company said.

Earlier this week the company said it was looking into a report that stolen customer information had been offered for sale on the internet.

Security blogger Brian Krebs wrote Tuesday that banks have reported data being pilfered from P.F. Chang’s locations in Florida, Maryland, New Jersey, Pennsylvania, Nevada and North Carolina.

Krebs gained attention late last year when he revealed the massive data breach at the Target retail chain.

The P.F. Chang’s breach occurred between the end of March and May 19, according to Krebs. Card data was being offered on a website favored by the Target hackers for $18 to $140 per card, Krebs reported.

“The items for sale are not cards, per se, but instead data copied from the magnetic stripe on the backs of credit cards,” Krebs wrote. “The most common way that thieves steal this type of card data is by hacking into cash registers at retail locations and planting malicious software.”

The alleged data intrusion suggests the willingness of hackers to go after relatively small companies.

P.F. Chang’s has about 200 locations in the U.S. and abroad. The company also operates Pei Wei Asian Diner, a more casual Asian restaurant chain with more than 170 U.S. locations. There is also a Pei Wei on Route 1 in the Princeton corridor.